Ben Horowitz, entrepreneur and investor is interviewed by John Heilemann of New York Magazine, Tuesday October 18, 2011, in front of a crowd at the Web2.0 Summit in San Francisco, Calif. Horowitz is best known for co-founding and running the enterprise sotware company Opsware, which is now owned by Hewlett-Parkard. He is now co-founder with Marc Andreessen of a venture capital firm called Andressen-Horowitz.

Photo: Lacy Atkins, The Chronicle

Ben Horowitz, entrepreneur and investor is interviewed by John...

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Bill Maris of Google Ventures is interviewed by John Battelle, Tuesday October 18, 2011, in front of a crowd at the Web2.0 Summit in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

Bill Maris of Google Ventures is interviewed by John Battelle,...

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Grahman Spencer, left and Bill Maris of Google Ventures is interviewed by John Battelle, Tuesday October 18, 2011, in front of a crowd at the Web2.0 Summit in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

Grahman Spencer, left and Bill Maris of Google Ventures is...

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Grahman Spencer, left and Bill Maris of Google Ventures is interviewed by John Battelle, Tuesday October 18, 2011, in front of a crowd at the Web2.0 Summit in San Francisco, Calif.

-- More data traveled across the Internet in 2010 than during all the preceding years combined.

Intel Vice President Kirk Skaugen tossed out this fact on the opening day of the Web 2.0 Summit, in what was a last-minute substitution for Chief Executive Officer Paul Otellini that many took as their first opportunity for a bathroom break.

But no other piece of information presented in the early sessions of the popular San Francisco conference so clearly underscored the stated theme of the event, "the data frame," or succinctly illustrated the magnitude of the force driving transformation in the online world today.

Hundreds of millions of consumers make daily confessions to the cloud, regularly offering up petabytes worth of personal data. They reveal their moods, wants, political leanings and tastes through tweets, Facebook likes, blog posts and story comments. They carry around a phone that discloses their daily habits and locations through Foursquare check ins, Instagram pictures or Google Maps guided trips.

As one industry leader after another made clear at Web 2.0, businesses and anyone else who can tap into this feedback loop gains unprecedented insight into the mind-sets of the masses. The data explosion is revolutionizing the ability to customize content, messages and ads across industries.

"The cloud, mobility and the shift to social," said Marc Benioff, the chief executive of Salesforce.com, in his onstage conversation with conference co-moderator Tim O'Reilly. "These three things together are creating a revolution in our industry."

And in other industries as well, as Web 2.0's speakers repeatedly demonstrated.

Music

In the first session on Monday, Sean Parker described how the music industry, transformed once by the digital distribution that Napster helped pioneer, is now being reorganized around social data.

The co-founder of Napster and founding president of Facebook (memorably portrayed by Justin Timberlake in "The Social Network") is now an investor in the British music service Spotify. It launched in the United States this summer and scored an incredibly valuable partnership with Facebook last month. Users can see the songs their friends are listening to or the playlists they create, offering a new approach to music discovery.

They can "consume and share without ever having bought the music. You can sample on an unlimited basis," Parker said. "And you find out about music through your friends."

He said it throws the traditional A&R function of the recording industry out the window, handing over scouting duties to fans. In fact, he said he didn't understand why any musician would bother with a traditional label these days.

Of course, Parker, who saw Napster kneecapped by the industry's legal departments, isn't exactly impartial on the subject. He said Spotify was a way of finishing what he started with Napster.

"I believe that the traditional gatekeepers of music ... were not selecting the music that best met the needs of the public," he said. "The best music being made wasn't being heard by most of the public."

Television

Deb Roy, the CEO of Bluefin Labs, provided a fascinating glimpse at the connection between social data and television.

Viewers are reacting to shows via Twitter, Facebook and blogs at a vastly accelerating rate. He noted that social media commentary on "Two and a Half Men" leaped by more than 12,000 percent from last season to the current one (thanks, one can assume in part, to the addition of Ashton Kutcher).

By analyzing the billions of reactions from millions of people, the Cambridge, Mass., company creates a detailed sense of reactions to shows as well as how those reactions shift the behavior and sentiment of others.

"All this conversation on the social Web is affecting what people are deciding to tune in to" and how they perceive what they watch, Roy said. "We can now link expression to impression."

It's kind of a Nielsen service for social reactions, offering insight not just into who's tuning in to what - but why and why not.

Bluefin can quantify the emotional reactions to episodes, pinpoint the heaviest crossover appeal between certain shows and provide a clear sense of the type of viewer tuning in. This offers producers a detailed picture of how people react to their content, and allows advertisers to make better educated guesses about where to sink their budgets.

"We know of no better way of knowing where that ad should run," Roy said.

Privacy

These companies are clearly improving their businesses by becoming more responsive to the needs of users, a consumer boon that's hard to quibble with. But there are legitimate questions about the consequences of this surging availability and the use of personal information. Some of the most critical policy debates of the information age involve data privacy and security.

"Today's creepy is tomorrow's necessity," he added, but without committing to the thought, tilting up the last word into a sort of question. It is, of course, an open question whether people's attitudes about privacy are fundamentally changing and whether they really should.

On Tuesday, Ann Cavoukian, information and privacy commissioner of Ontario, Canada, and co-author of several books on privacy, stressed that companies should stop thinking of privacy and business interests as opposing concepts.

She said the firms that will be most successful are those that bake privacy features into their products from the start, giving users control over their data and transparent choices about what they share. The costs to the business brand and bottom line are far higher when a company has to fix practices in the wake of a data breach or regulatory slap.